BOOM lost power!

[DVS_Freestyler]

well i just got my 400ex yesturday from inacoma99 and its a great quad!!! well heres my question. i was out riding today, put about 3 hours on, all of a sudden it lost power. im sure its nothing major, maybe a pluged gas line or some other crap, but just to make sure i'll ask on here and see what you guys think. what could be the problem? i was riding and it just gave up it seemed. it runs and idles but when you give it a little gas it will sputter or cut out. any ideas? im goign to adjust the valves tonight so before i get started maybe i can figure out my problems first.

[300EX KING]

if its a new 400ex like 2002 then it might need some time for the engine to break in.

[DVS_Freestyler]

its a 2000, ran good all day, just all of a sudden lost power.

[RideRed04]

ask inacoma if he ever had any problems with it. congrats on getting it! It will be great for the big ride!

[Leo]

check the simple stuff first...

fuel line restriction, main jet vibrated loose (it happens)..

also look the air boot between the carb + cyl head over very closely for cracks...

Leo

[nakomis0]

sounds like the main jet might of feel out to me too.

[400exBro]

cly. head cracks:( that don t sound to good, what happens if it is crack.............
what are the chances..............................
thanks
Bro

[Texan32]

if its not something obvious, you might want to check the accelerator pump on the carb. If its not pumping in enough gas....

[Blaster250x]

I think Leo is talking about cracks in the rubber intake manifold,not in the cylinder or head...

[DVS_Freestyler]

thanks guys, im going to take the carb apart tonight, i'll give you all updates. so far ive been very impressed with the 400ex, just not used to the 4 stroke because of my experience with 2 strokes. thanks again

[DVS_Freestyler]

thanks leo, your a life savor. i checked my carb out for anything loose, and by god i tipped the carb over and heard the ting sound. ok something was up i thought, so i proceeded to take apart the carb, and to my suprise i found the 2 screws that held the carb needle in place backed themselves out. there was 2 screws bouncing around in there and the needle itself. boy was i happy to find everything in good shape yet and not destroyed. so i put her all together, prayed and she fired up!!! woohoo, job well done haha, well thanks leo alot, i really didnt think something that odd could happen. :cool:

[DVS_Freestyler]

oh yeah before i get any farther, im on the home computer and this one is under my brothers name (LBZ) im too lazy to change it. this is actually jon (wiredcinqmars) and the 400ex is mine, my brother has the R

[BornOnFire]

The same thing happened on my 400EX after I did some work on it. It was running fine when all of a sudden, no power. I have had the carb apart 5 times with no fix yet. Please, if you will, let me know what you find out!:D
Perhaps we have the same problem! I am trying to avoid taking it back to the dealer!

[Leo]

I think he is talking about the 2 screws that attach the arm to the slide...

A quick check would be to hold the throttle wide open, if the slide doesn't open up, then you know somethings up :D

Leo

[Wingnut]

I had the exact same problem! However, I never did find that second screw.:eek:

[BornOnFire]

Check beneath the arm for that screw. That's where I found mine hiding!!